A particle beam therapy is performed by irradiating affected tissue with a particle beam so as for the affected tissue to be damaged, and is one of radiation therapy in a broad sense. Regarding a particle beam such as a proton, a heavy ion beam, etc., unlike other radiation such as γ-ray, X-ray, a depth range of applying dose can be adjusted by energy of a particle beam, dose can be applied according to a three-dimensional shape of an affected part. Therefore, especially, it is required for an accelerator for a particle beam therapy system to supply a particle beam having accurate energy and orbit.
An accelerator comprises deflection electromagnets for forming an orbit, an acceleration cavity for accelerating a particle beam using a high-frequency, and vacuum ducts which are passages for a particle beam to pass through, etc. Magnetic fields of the deflection electromagnets change according to predetermined patterns with acceleration of a particle beam (energy growth). At the same time, an orbit frequency of a particle beam changes. Therefore, in order to accelerate a particle beam stably, it is necessary to control a frequency or amplitude (intensity) of a high-frequency signal, which is applied to the acceleration cavity, according to a predetermined pattern.
In order to simplify the above-mentioned control, for example, a RF control device, by which a frequency reference signal of a high-frequency signal which is made by a computer in advance is stored and is sequentially read out during operation is proposed (for example, refer to Patent Document 1). However, according to the above-mentioned system, data volume is vast and data conditioning is not easy and number of components is also great. Therefore, a high-frequency control device, wherein an operation pattern of an accelerator is divided into a flat stable region and a region having a flat acceleration part, and a wave-form data of each region is used to control is proposed (for example, refer to Patent Document 2).
On the other hand, an irradiation method of a particle beam therapy is broadly divided into a broad irradiation method in which whole of an affected part of a patient which is an irradiation subject is irradiated simultaneously with a particle beam and a scanning irradiation method in which a particle beam is scanned to irradiate. In a case of a broad irradiation method, a particle beam to be irradiated has definite energy. On the other hand, in a case of a scanning irradiation method, energy of a particle beam is changed so as to irradiate a wide range of depth direction. Energy of a particle beam is changed by changing a magnetic field of an accelerator and a pattern of a high-frequency. Therefore, in a case of a scanning irradiation method, it is necessary to set an operation pattern of an accelerator in accordance with energy and intensity for each energy and intensity. Consequently, in comparison with a broad irradiation method, it is necessary to store more operation patterns.